Apparatus for straight line oscillation of a wire guide

ABSTRACT

Apparatus for oscillating a wire guide carried by a wire feed carriage which moves axially of a rotating concrete pipe core to apply prestressing wire to the core. The oscillating mechanism includes a four bar pantograph with the wire guide mounted on one end of one link of the pantograph to provide straight line movement of the wire guide parallel to the axis of the core being wrapped as the wire guide is oscillated.

lJn-ited States Patent Marcum, Jr.

[ Jul 9, 1974 [54] APPARATUS FOR STRAIGHT LINE 3,052,419 9/1962 Huck242/722 OF A W GUIDE ZE'fi 2/1221 8212 1;; 12118 g1 [7 v n glgr M m,Jr-,n rv1ll 3,724,768 4/1973 Breitfuss et al. 242/722 x [7 Assigneel PriceBrothers p y Dayton, Primary Examiner-Stanley N. Gilreath 3 Ohm 4.9145284891 11. 9'1IEUWIEFPPQLHEKEEQQB2581. [22 Filed: 061. 3, 1972 [21]Appl. No.1 294,624 57 ABSTRACT Apparatus for oscillating a wire guidecarried by a f ii ig i wire feed carriage which moves axially of arotating g concrete pipe core to apply prestressing wire to the [58]Field of Search 242/721, 7.22, 7.23, 7.01,

242/158 R 158 F 158 B 158 2 158 4 core. The osclllatmg mechamsm mcludesa four bar 4 a anto a h with the wire uide mounted on one end 138/172176 p P g of one link of the pantograph to provide straight linemovement of the wire guide parallel to the axis of the [56] u TE g grxggs ggENT's I core being wrapped as the wire guide is oscillated.3,039,707 6/1962 Beck et al 242/I5 .2-x 8 Claims, 6 Drawing FiguresHYIgmUPLIC 22 v J20 2 38 46 SERVO AMPLIFIER PIPE SIZE CONTROL I I2BEVELLENGTH ANALOG T0 FULL z I I I "CONTROL DIGITAL R g 4 i (N SELECT)CONYERTE 54 52 V r'fi'fi" LINEARIZING sYNcRo 3 BY 556 51311 NETWORK "-34TRANSMITTER 6 j I R0 to MULTIPLYING DIFEQRCETGQTIAL l lrE /COS DIGITALTOANALOG TRANSMITTER CONVERTER CONVERTER 32 LE 26 3 0 as 28 I IPAIENTEDJUL 919m SHEEY 2 0F 3 m wE SHEET 3 BF 3 FIG IHII

APPARATUS FOR STRAIGHT LINE OSCILLATION OF A WIRE GUIDE BACKGROUND OFTHE INVENTION Prestressed concrete pipe is made by wrapping prestressingwire under tension about a pipe core. In the majority of pipe sectionsmanufactured, the ends of the pipe extend at right angles to thelongitudinal axis of the pipe. In some case, however, particularly whereit is desiredto make a slight change in grade or direction of the pipeline as .it is installed, one end'of the pipe section may be slanted, orbevelled, with respect to the longitudinal axis of the pipe. Pipesections of this type are referred to as bevel pipe.

Bevel pipe will either be full bevel or half bevel. In a full bevel pipethe longer side is l inch longer for each foot of internal diameter thanthe shorter side. For example, in a 48 inch, full bevel pipe, the longerside is 4 inches longer than the short side, while in a 36inch fullbevel pipe the longer side is 3 inches longer than the shorter side. Ina half bevel pipe the long side of the pipe is one-half inch longer foreach foot of internal diameter than the short side of the pipe.

It will be apparent that in wrapping prestressing wire on bevel pipe,although the spacing between adjacent wraps should be uniform along amajor portion of the length of the pipe, some variation in spacingbetween adjacent wraps on the long and short sides of the pipe must bemade atthe bevelled end to accommodate the difference in lengths betweenthe opposite sides of the pipe.

In the past this variation in spacing has been accomplished by themachine operator visually checking the spacing between adjacent wirewraps and jogging the wire wrap carriage at the bevel end of the pipe toprovide unequal spacing of the wire wraps at the long and short sides ofthe pipe.

More recently, apparatus has been designed for eliminating the necessityof relying on operator judgment I for obtaining the desired wire wrapspacing on the pipe. In apparatus of this type a pivotally mounted armcarrying a wire guide at one end is automatically oscillated by controlmechanism as the carriage on which the arm is mounted moves along thebevel end of the pipe core being wrapped. For example, see U.S. Pat.Nos. 3,052,419; 3,052,226; and 3,587,659.

It will be noted, however, that where variation in wrap spacing isobtained by feeding the wire through guide sheaves attached to apivotally mounted arm, an additional, unwanted variation is introduced,since the guides sheaves are not moving parallel to the pipe core but inan arc. This becomes particularly noticeable where pipe cores of largediameter are being wrapped.

It will be seen, therefore, that with mechanism of this type, either thevariation in wrap spacing from that desired which results at the bevelend must be acceptable or, control mechanism must be provided that cancompensate for these deviations by controlling other variables of theprocess.

SUMMARY or THE INVENTION Bevel wrapping apparatus in accordance with thepresent invention provides a system for automatically wrapping bevelpipe wherein the oscillation of a wire guide carried by a wire feedcarriage moving parallel to the axis of the pipe core is oscillated witha straight line movement which is also parallel to the core axis. As aresult, variations in wrap spacing from the spacing desired, which wouldoccur if the wire guide was merely carried by a pivoted link, areavoided.

The wire guide incorporates a four bar pantograph mechanism in which afeed link carries the wire guide and is actuated by a drive link poweredby a double acting hydraulic or pneumatic piston and cylinder. To insurethat the outer end of the feed link moves with a straight line motion,pairs of rollers having mutually perpendicular axes are mounted on thedrive link and run along trackways extending perpendicular to each otherbut parallel to the axis being wrapped.

The rollers are mounted on the drive at the point of intersection'of thedrive link with a line passing through a fixed pivot connection of twoother links of the system and the wire guide sheaves. As a result, thelinkage system provides a true axial movement of the wire guide sheaves,eliminating both inaccuracy in wrap spacing at the bevel end of the pipeand the necessity of providing additional control mechanism tocompensate for nonlinear movement of the wire guide sheaves.

BRIEF DESCRIPTION THE DRAWINGS FIG. 1 is a block diagram of the systemof the present invention;

FIG. 2 is a side view of the bevel wire control mechamsm;

FIG. 3 is a rear view of the mechanism of FIG. 2;

FIG. 4 is a view taken on line 44 of FIG. 3;

FIG. 5 is a view taken on line 5-5 of FIG. 4; and

FIG. 6 is a perspective view of the pantograph linkage of the bevel wirecontrol mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring initially to thesimplified block diagram shown in FIG. I of the drawings, it will beseen that, in accordance with the present invention, a pipe 10 is placedon a platform 12 to be rotated by a drive mechanism 14. The drivemechanism also supplies power through a variable ratio drive 16 to acarriage drive mechanism 18 driving a wire feed carriage 20. Thevariable ratio drive therefore controls the pitch of the wire at it iswrapped onto the pipe by controlling the rate at which the carriage 20moves vertically as the pipe is rotated.

A bevel wire control mechanism, shown generally at 22, is mounted oncarriage 20, and, as described below in detail, applies the wire wrapsto the pipe 10. For present purposes it will be noted that the bevelwire control mechanism is so designed that the point at which the wireis fed from the mechanism to the pipe moves parallel to the axis of thepipe. This is especially important when wrapping wire on large diameterpipe (e.g. 196 inch pipe).

The rotational position of the pipe is sensed by a syncro transmitter 24(Vernitron Corp., type VCX 23/ 36- 6C), the rotor of which makes onerevolution for each revolution of the pipe. Thesyncro transmitter 24 iselectrically connected to a syncro differential transmitter 26(Vernitron Corp. type VCDX 23/38-6C). The rotor 28 of the syncrodifferential transmitter does not rotate with the rotor of snycrotransmitter 24 but is a fixed rotor which may be adjusted initially bythe operator to align the syncro transmitter 24 electrically with theorientation of the pipe so that the pipe and the syncro signals areproperly aligned at the beginning of a wire wrap operation.

Each pipe is initially mounted for wrapping with its wire anchor,located on the long side of the pipe, at the point of tangency of thewire from the bevel wire control 22. Due to the large size of the pipeand the consequent difficulty in placing the pipes on the platform 12precisely, an electrical correlation between the pipe position and thesyncro transmitter is provided by the manual positioning of the rotor28.

The electrical output of the syncro differential transmitter 26 is arepresentation of the angle of the pipe with respect to its startingposition. This output is connected to a sine/cosine converter 30 (NatelEngineering, type 43l-3B-60-115), the outputs of which are electricalsignals representing the sine and cosine of the angle of the pipe withrespect to its starting position, these signals being of a predeterminedamplitude and of a frequency equal to the rotational frequency of thepipe.

One output of the sine/cosine converter 30 (e.g., the cosine output) isapplied to a summing amplifier 32 whereit is combined with a signal froma linearizing network 34. The output of the linearizing network 34 is asignal which is a function of pipe diameter and is used to provide anoffset voltage to allow this invention to accommodate an extremely largerange of sizes. The output of the summing amplifier 32 is applied as aninput to a multiplying digital to analogue converter 36 (Data DeviceCorp., type UDAC-l1-3). The output waveform of converter 36 is identicalto its input from amplifier 30 except that the output waveform isreduced in amplitude by a ratio which is initially determined by pipesize and thereafter reduced progressively as wire is wrapped onto thepipe.

The output waveform from converter 36 is applied as one input to asecond summing amplifier 38. The other input to the amplifier 38 is asignal generated by a linear variable differential transformer (LVDT)40(mfg. by Schaevitz), the output of which represents the position of ahydraulic piston in a bevel wrap control 22. The difference between thecontrol signal from converter 36 and the actual position signal fromLVDT 40 is an input signal to servo amplifier 42 (Analog Devices, Inc.,type 408). The output of the servo amplifier 42 controls a servo valve44 which in turn controls hydraulic fluid from a hydraulic pump 46 tothe bevel wrap control 22. This, as will presently be explained indetail, causes a feed link of the control 22 to follow or track thecontrol signal output of the digital to analogue converter 36 andtherefore will position the wire relative to the carriage mechanismunder the control of that signal.

. A pipe size control 50 is provided to permit the invention toaccommodate pipe of various sizes. The pipe size control 50 is a -turnpotentiometer which provides means for presetting the initial amplitudeof the output signal from the digital to analogue converter 36. Thepotentiometer is connected to an amplifier 52 which is selectable in theembodiment of the invention shown herein to have a gain either ofone-tenth or onetwentieth. A gain of one-tenth corresponds to a fullbevel position of switch 54 while a gain of onetwentieth corresponds toa half bevel position of the switch. Amplifier 52 is connected to ananalogue to digital converter 56 (Datel, type ADC-E123) whichcontinuously converts the analogue input from amplifier 52 into a 10 bitdigital or binary word. This 10 bit word is used as a preset input toup-down counter 58.

The position of the wire feed carriage 20 is monitored by an outputshaft encoder 60 which produces a predetermined number of pulses foreach increment of movement of the carriage. These pulses are applied toa divide by N counter 62. The value of N is determined by the length ofthe bevel to be applied to the pipe 10 and may be selected by a selectorswitch 64. In the embodiment shown in FIG. 1, the number N may be anyinteger from one to 63.

Switch 64 is actually a six position selector switch which is used toselect the integers 2, 4, 8, 16, 32 and 63. The larger the value of N,the greater the number of pulses (representing a greater length oftravel of the carriage) which will be required to be applied to theup-down counter 58 to reduce its present value (as detennined by thepipe size control 50) to zero. Once the preset counter reaches the valueof zero, the output of the digital to analogue converter 36 will also bezero which therefore terminates the bevel wrap operation.

Turning now to FIGS. 2 through 6 of the drawings, the bevel wire controlmechanism 22 will be described. As seen in FIG. 6 of the drawings, thebevel wire control mechanism includes a pantograph linkage whichconsists of a feed link 72, a drive link 74, a spacer link 76 and aguide link 78. The drive link 74 is formed as a pair of side plates 80joined by a cross bar 82 and having openings 84 therethrough for thereception of a shaft 86 which pivotally attaches thereto the feed link72 intermediate its ends.

The spacer link 76 is bifurcated at one end thereof to provide a pair ofarms 88 having openings therethrough to receive pivot shafts 92 whichpivotally attach the bifurcated end of the spacer link to the upper endsof the side plates 80 of the drive link 74. At its opposite end thespacer link is pivotally mounted between the spaced side plates 94 ofthe guide link 78.

The side plates of guide link 78 are joined by a cross bar 96 and ashaft 98 extends through openings in the upper ends of the side plates94 and an opening in one end 102 of the spacer link 76. The end 104 ofthe feed link 72 is provided with an opening therethrough and isreceived between the lower ends of the side plates 94, with the openingin feed link 72 aligned with openings 106 in the side plates 94. A shaft108 passes through the aligned openings in links 72 and 78 to form apivotal attachment between them at this point.

The opposite end of the feed link 72, as seen in FIGS. 2 and 3, has agrooved guide sheave 110 rotatably mounted thereon and a guide sheavelink 1 12 pivotally attached thereto, as at 114. The guide sheave link112 includes a pair of side plates 116 interconnected at their upperends by cross bar 118 and an abutment member 120. Joumalled between thelower ends of the side plates 116 is a second grooved guide sheave 122.Mounted on an upper surface of the feed link 72 is a threaded block 124receiving an attaching bolt 126 which bears at one end against theabutment 120. With this construction it will be seen the spacing betweenthe grooved guide sheaves 110 and 122 may be adjusted.

Turning now to FIGS. 2 through 5, it will be seen that the wire bevelcontrol mechanism also includes a supporting framework 128, on which ismounted a hydraulic piston and cylinder 130 by means of the trunion 132and a pillow block 133. A .piston rod 134 protrudes from the lower endof the cylinder 135 and is attached at its inner end to a piston, notshown. The hydraulic piston and cylinder 130 is of the double actingtype, for example, the type manufactured by the Parker Hannifin CompanyNo.

At its lower end the piston rod is threaded and received in aninternally threaded knuckle 136. The lower end of knuckle 136 is ofsplit construction and receives a cross shaft 137 therethrough with thesplit end of the knuckle being clamped to the shaft 137 by means ofbolts or the like 138. Ourwardly' of the knuckle 136 the shaft isjoumalled, as at 140, in the side plates 80 of the drive link 74.

At its outer ends the shaft 137 has attached thereto roller brackets142. Each bracket 142 rotatably supports a pair of rollers 144 whichengage trackways 146 on the supporting framework 128. Each bracket 142also journals a second pair of rollers 148 which engage trackways 150extending parallel to trackways 146 but disposed perpendicularlythereto.

Bearing blocks 152 are mounted on one face of the supporting framework128 by means of bolts 154 passing through slotted openings 155 in thebearing blocks. A pair of adjusting bolts 156 are threaded throughblocks 158 and bear on a lower surfaces of the bearing blocks 152 toprovide a limited amount of vertical adjustment. As best seen in FIG. 2of the drawings, outer ends of the shaft 98 are joumalled in bearingblocks 152 to pivotally attach the linkage 70 to the supportingframework 128.

As noted above, theflow of pressurized fluid to opposite sides of thepiston of the hydraulic piston and cylinder 130 is controlled throughthe servo valve 44, which, as seen in FIG. 4 of the drawings, directsflow alternatively through pressure lines 162 and 164. Movement of thepiston within the cylinder 135 is sensed by means of the LVDT 40, sinceits probe 166 is directly connected through arm 168 to an upwardlyprojecting rod 170 attached to the piston.

With the above construction, it will be seen that the servo valve 44 maydirect pressurized fluid to either side of the piston and cylinder 130through the lines 162 and 164, causing the piston to move within thecyl- 1 inder. This movement is sensed by the LVDT 40 which transmits asignal to the amplifier 38 representing the position of the piston inthe cylinder.

Movement of the piston rod 134 in a vertical plane is transmitted to thedrive link 74 by means of the knuckle 136 and shaft 137. Since theintersection of the links 76 and 78 is fixed and since the guide end ofthe feed link 72 and the axes of shafts 137 and 98 lay on a straightline, movement of the outer end of the feed link 72 will be parallel tothe movement of the shaft 137 in accordance with well known principlesof pantograph operation.

Additionally, since the shaft 137 is restrained by the rollers 144, 148and cooperating trackways on the sup porting framework 128 and can onlymove in a vertical direction, the guide end of the feed link also iscapable of only vertical movement. As a result, the guide end of thefeed link moves axially of the pipe 10 being wrapped rather than in anarc, as would be the case if a pivotally mounted arm were utilized.

From the above construction, it will be seen that the presentinventionprovides wire wrapping mechanism which provides for infiniteadjustability with respect to pipe diameter and the amount of bevel ofthe pipe being wrapped and in which the wire guide mechanism v wirewraps at the bevel end of said core varying from a maximum at the longside of said core to a minimum at the short side thereof, includingmeans for rotating said core about the longitudinal axis thereof, a wirefeed carriage, means for moving said carriage along a path parallel tothe axis of rotation of said core at a speed proportional to therotational speed of said core about said axis, wire guide means mountedon said carriage, and means for oscillating the wire guide meansrelative to said carriage as said carriage moves along said coreadjacent said bevel end thereof to vary the spacing between adjacentwire wraps, the improvement wherein the means for oscillating said wireguide means comprises:

a. a linkage system including a feed link carried by said wire feedcarriage,

b. means mounting said wire guide means on said feedlink, and r c. meansfor oscillating saidfeed link with said guide means moving parallel tosaid rotational axis of said core.

2. The apparatus of claim 1 wherein:

a. said linkage system is a pantograph and said wire feed link is onelink thereof.

3. The apparatus of claim 2 wherein said pantograph further comprises:

a. a guide link,

b. a spacer link,

c. means pivotally mounting said guide and spacer links on said carriagefor pivotal movement about a pivot point fixed with respect to saidcarriage,

d. a drive link pivotally attached to said spacer link at a pointthereon spaced from the pivotal connection of said spacer link to saidcarriage,

e. means pivotally attaching said wire feed link to said guide link at apoint thereon spaced from the pivotal connection of said guide link tosaid carriage, and

f. means pivotally attaching said drive link to said feed link at apoint intermediate the pivotal attachment of said guide link thereto andsaid wire guide means.

4. The apparatus of claim 3 wherein said oscillating means comprises:

a. means engaging said drive link at a point thereon intermediate thepoints of pivotal attachment thereof to said spacer link and feed link.

5. The apparatus of claim 4 further comprising:

' a. means for restraining said point on said drive link againstmovement in directions other than parallel to said core axis.

6.The apparatus of claim 5 wherein:

a. said point on said drive link lies substantially on a straight lineconnecting said pivot point fixed with respect to said carriage and saidguide means.

7. The apparatus of claim 4 wherein said means engaging said drive linkcomprises:

a. a double acting piston and cylinder,

b. a piston rod attached to said piston and projecting from saidcylinder, and

c. means interconnecting said piston rod and said drive link at saidpoint thereon.

8. In apparatus for wrapping prestressing wire about a bevel pipe coreincluding means for rotating a core about its axis and a carriagemovable along a path parallel to said axis the improvement comprising:

a. a supporting framework mounted on said carriage,

b. a double acting piston and cylinder including a piston rod attachedto said piston and projecting outwardly of said cylinder mounted on saidframework,

c. a source of fluid under pressure,

d. means for directing said fluid into said cylinder on opposite sidesof said piston,

e. means for controlling said fluid directing means in response to thedesired spacing of wire wraps on said core,

' f. a drive link pivotally attached intermediate its ends to anoutwardly projecting end of said piston rod,

g. track means mounted on said framework and extending parallel to saidaxis of rotation of said core,

h. means attached to said drive link at said point of attachment thereofto said piston rod and movable along said track means only in adirection parallel to the axis of rotation of said core,

i. a spacer link pivotally attached at one end to said supportingframework and at an opposite end thereof to one end of said drive link,

j. a guide link pivotally attached at one end thereof to said supportingframework at the point of attachment of said spacer link to saidframework,

k. a feed link pivotally attached at one end to an end of said guidelink opposite said one end thereof,

1. means pivotally attaching said feed link intermediate its ends to anend of said drive link opposite said one end thereof, and

m. guide means mounted on an end of said feed link opposite said one endthereof. =i

1. In apparatus for wrapping prestressing wire about a bevel pipe corewith the spacing between adjacent wire wraps at the bevel end of saidcore varying from a maximum at the long side of said core to a minimumat the short side thereof, including means for rotating said core aboutthe longitudinal axis thereof, a wire feed carriage, means for movingsaid carriage along a path parallel to the axis of rotation of said coreat a speed proportional to the rotational speed of said core about saidaxis, wire guide means mounted on said carriage, and means foroscillating the wire guide means relative to said carriage as saidcarriage moves along said core adjacent said bevel end thereof to varythe spacing between adjacent wire wraps, the improvement wherein themeans for oscillating said wire guide means comprises: a. a linkagesystem including a feed link carried by said wire feed carriage, b.means mounting said wire guide means on said feed link, and c. means foroscillating said feed link with said guide means moving parallel to saidrotational axis of said core.
 2. The apparatus of claim 1 wherein: a.said linkage system is a pantograph and said wire feed link is one linkthereof.
 3. The apparatus of claim 2 wherein said pantograph furthercomprises: a. a guide link, b. a spacer link, c. meaNs pivotallymounting said guide and spacer links on said carriage for pivotalmovement about a pivot point fixed with respect to said carriage, d. adrive link pivotally attached to said spacer link at a point thereonspaced from the pivotal connection of said spacer link to said carriage,e. means pivotally attaching said wire feed link to said guide link at apoint thereon spaced from the pivotal connection of said guide link tosaid carriage, and f. means pivotally attaching said drive link to saidfeed link at a point intermediate the pivotal attachment of said guidelink thereto and said wire guide means.
 4. The apparatus of claim 3wherein said oscillating means comprises: a. means engaging said drivelink at a point thereon intermediate the points of pivotal attachmentthereof to said spacer link and feed link.
 5. The apparatus of claim 4further comprising: a. means for restraining said point on said drivelink against movement in directions other than parallel to said coreaxis.
 6. The apparatus of claim 5 wherein: a. said point on said drivelink lies substantially on a straight line connecting said pivot pointfixed with respect to said carriage and said guide means.
 7. Theapparatus of claim 4 wherein said means engaging said drive linkcomprises: a. a double acting piston and cylinder, b. a piston rodattached to said piston and projecting from said cylinder, and c. meansinterconnecting said piston rod and said drive link at said pointthereon.
 8. In apparatus for wrapping prestressing wire about a bevelpipe core including means for rotating a core about its axis and acarriage movable along a path parallel to said axis the improvementcomprising: a. a supporting framework mounted on said carriage, b. adouble acting piston and cylinder including a piston rod attached tosaid piston and projecting outwardly of said cylinder mounted on saidframework, c. a source of fluid under pressure, d. means for directingsaid fluid into said cylinder on opposite sides of said piston, e. meansfor controlling said fluid directing means in response to the desiredspacing of wire wraps on said core, f. a drive link pivotally attachedintermediate its ends to an outwardly projecting end of said piston rod,g. track means mounted on said framework and extending parallel to saidaxis of rotation of said core, h. means attached to said drive link atsaid point of attachment thereof to said piston rod and movable alongsaid track means only in a direction parallel to the axis of rotation ofsaid core, i. a spacer link pivotally attached at one end to saidsupporting framework and at an opposite end thereof to one end of saiddrive link, j. a guide link pivotally attached at one end thereof tosaid supporting framework at the point of attachment of said spacer linkto said framework, k. a feed link pivotally attached at one end to anend of said guide link opposite said one end thereof, l. means pivotallyattaching said feed link intermediate its ends to an end of said drivelink opposite said one end thereof, and m. guide means mounted on an endof said feed link opposite said one end thereof.